Bedbugs’ genes may be the reason the pest is so hard to get rid of. (Photo: Creative Commons)

To kill a bedbug or its eggs, humans must expose it to temperatures of -16 degrees Celsius (3.19 Fahrenheit) for a minimum of 80 hours, according to a new entomological study released Sunday, suggesting the pests to be more impervious to freezing temperatures than previously thought. The study may also lead to more specific recommendations on how to freeze out bedbugs.

It takes temperatures below -15 degrees Celsius (5 degrees Fahrenheit) at three and a half days to control all life stages of bedbugs (Cimex lectularius), entomologists wrote in an article in the December issue of Journal of Economic Entomology, while temperatures below -20 degrees Celsius (-4 degrees Fahrenheit) require 48 hours.

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Bedbugs, like many other insects, can protect themselves from freeze injury by lowering the freezing point of their body fluids. Not only are bedbugs hardy, the entomologists found, their eggs are too: Some bedbug eggs survived in short-term exposures to -25 degrees Celsius (-13 degrees Fahrenheit). For those who put bug-infested items in a freezer, the entomologists recommend they keep them there for two to four days, depending on the freezer's temperature.

The study lends specificity to experts' recommendations of what constitutes a killing temperature for a bed bug and its eggs, and for how long. An entomologist, for instance, writing on The University of Kentucky College of Agriculture's website, says bedbugs will succumb to cold temperatures below 32 degrees Fahrenheit, if maintained for one to two weeks. The U.S. Environmental Protection Agency (EPA) maintains on its website that putting infested items outside in freezing temperatures can kill bedbugs after several days when the temperature is 0° Fahrenheit (-17.7 Celsius), and almost a week when the temperature is 20 degrees Fahrenheit (-6.6 Celsius). Though technically freezing, 20 degrees Fahrenheit is almost 17 degrees warmer than what the study determines was a good killing temperature for bedbugs.